Modern cognitive radio technology allows dynamic spectrum sensing, spectrum management, mobility and spectrum sharing, to mention few. Classical cognitive radios change frequency channels when the interference level or other parameters associated with operation can be improved by moving to another frequency. The modern signal processing and multiple antenna technologies, however, allow expanded cognitive operation where receiver algorithms and transmit waveforms are dynamically adjusted for an operational environment.
Radio spectrum is a limited resource. A large amount of spectrum is required to deliver services that are associated with modern wireless personal communications. Typical examples are smart phone Internet applications, wireless streaming audio, and video, to mention a few. These services consume large amounts of spectral resources causing both financial and spectrum policy issues.
Typically these services are provided using licensed spectrum. The financial burden from licensing can be defined as a cost of billions of dollars, even for a relatively small amount of spectrum, when compared to freely available unlicensed spectrum. The licensing, however, is required to make sure that current 1G to 4G radio technologies have the coordinated access they require to deliver quality of service that is adequate for an end user application.
Currently in United States there are several hundred MHz of unlicensed spectrum that can be used for delivering wireless services to consumers, however, traditional radio technologies typically suffer from interference from uncoordinated access from other unlicensed users. A novel radio technology is required that can deliver service while being highly resistant to interference while also creating as little interference as possible to other users in the unlicensed band.
No single signal processing or radio solution provides a complete answer to the problem described, however by combining multiple technologies a cognitive radio network can be engineered. The invention described in this disclosure is one piece of a complete cognitive radio network technology.